1. Field of the Invention
The present invention relates to an injector.
2. Description of the Related Art
An injector for sending a fluid such as a chemical liquid or ultrapure water, under pressure, is often built into various apparatuses used, for example, on a semiconductor production line. A conventionally known injector of this type comprises an inlet and an outlet for the fluid to be sent under pressure (hereinafter sometimes referred to as the pressured fluid), two chambers, two inlet portions establishing communication between each chamber and the inlet, a body formed with two outlet portions for establishing communication between each chamber and the outlet, and a pressure application mechanism having at each end thereof a diaphragm to be arranged in each chamber, wherein a working fluid such as a gas is supplied into the chambers so that the pressure application mechanism is reciprocated and the pressured fluid in the chambers is discharged from the outlet.
The injector having the conventional structure described above, however, poses the problem that the internal pressure of each chamber sharply changes when the pressure application mechanism is reciprocated, or especially when switching the supply of the working fluid for reciprocating the pressure application mechanism. This sharp pressure change has caused various inconveniences such as a shortened service life of the component parts including the pressure application mechanism.
Also, in the conventional structure described above, the supply of the working fluid for reciprocating the pressure application mechanism is switched at a time point when a stroke end detecting switch or a sensor built in the body detects the stroke end of the pressure application mechanism, or is switched mechanically utilizing the rise of the internal pressure of the chamber supplied with the working fluid, upon arrival at the stroke end of the pressure application mechanism. As a result, the discharge pressure of the pressured fluid at the outlet is substantially zero when the pressure application mechanism is inverted in operation, thereby undesirably causing a large pulsation in the discharge pressure. Also, the aforementioned switching of the supply of the working fluid for reciprocating the pressure application mechanism makes it very difficult to change the discharge flow rate from the injector. If, for example, that the injector is used for sending the fluid under pressure in a semiconductor production line, a large pulsation is liable to adversely affect the yield of the semiconductor products as the fluid (a liquid in this case) after being scattered and fouled is attached to the semiconductor wafer or causes etching irregularities.
Further, when switching the supply of the working fluid for reciprocating the pressure application mechanism as described above, the diaphragm portion of the pressure application mechanism comes into harsh contact with the inner wall of the chambers upon arrival at the stroke end, thereby shortening the service life of the pressure application mechanism.
Furthermore, in the conventional structure described above, if the pressure application mechanism is stopped with the center thereof displaced from the intermediate position of the longest reciprocation range (reciprocation range for normal operation) thereof when the injector operation is stopped, i.e. when the supply or discharge operation of the working fluid is stopped after restart of the injector operation, the center of the reciprocating motion of the pressure application mechanism is deflected to one of the chambers, with the result that the pressure application mechanism is reciprocated with the reciprocation range thereof changed from that for normal operation. Thus, the discharge flow rate (discharge pressure) changes before and after the operation stop of the injector. Generally, the two chambers are set to the same discharge flow rate. In the case where the center of reciprocation of the pressure application mechanism is displaced after restart of the operation as described above, however, the discharge flow rate (discharge pressure) varies between the two chambers.
In addition, the conventional structure described above harbors the problem that the body must be segmented into a multiplicity of parts or the volume of the body increases to such an extent as to make a bulky injector.
The present invention has been developed in view of the aforementioned points, and the object thereof is to provide an injector having a simple, compact structure in which the pressure change in the chambers is relaxed at the time of reciprocating motion of the pressure application mechanism thereby to lengthen the service life of the component parts including the diaphragm portion, and a stable discharge flow rate with a small pulsation is obtained while at the same time securing the same discharge flow rate free of the variations.
According to a first aspect of the invention, there is provided an injector (I) comprising a body (B) including therein:
a first outer inlet portion (13) for a fluid to be sent under pressure (F);
a first outer outlet portion (14) for the fluid sent under pressure;
a connecting inlet portion (21) communicating with the first outer inlet portion;
a connecting outlet portion (22) communicating with the first outer connecting outlet portion;
a second outer inlet portion (31) communicating with the connecting inlet portion;
a second outer outlet portion (32) communicating with the connecting outlet portion;
a first chamber (40) including a first intake portion (41) communicating with the first outer inlet portion and a first discharge portion (42) communicating with the first outer outlet portion;
a second chamber (50) including a second intake portion (51) communicating with the second outer inlet portion and a second discharge portion (52) communicating with the second outer outlet portion;
a first intake check valve (61) interposed between the first outer inlet portion and the first intake portion for causing the pressured fluid to flow toward the first intake portion;
a first discharge check valve (66) interposed between the first discharge portion and the first outer outlet portion for causing the pressured fluid to flow toward the first outer outlet portion;
a second intake check value (71) interposed between the second outer inlet portion and the second intake portion for causing the pressured fluid to flow toward the second intake portion;
a second discharge check valve (76) interposed between the second discharge portion and the second outer outlet portion for causing the pressured fluid to flow toward the second outer outlet portion;
a pressure application mechanism (80) including a first pressure application diaphragm portion (81) with the outer peripheral portion thereof fixed on the inner wall (40a) of the first chamber and a second pressure application diaphragm portion (82) with the outer peripheral portion thereof fixed on the inner wall (50a) of the second chamber, the first pressure application diaphragm portion (81) and the second pressure application diaphragm portion (82) being arranged to be integrally movably by a coupling (83);
a working fluid influx/outlet portion (90) open to at least one of the first chamber and the second chamber for causing a working fluid (A) for reciprocating the pressure application mechanism to flow into or flow from at least one of the first chamber and the second chamber;
a first urging diaphragm portion (100) arranged on the outer wall surface (40b) of the inner wall of the first chamber for pressing the first pressure application diaphragm portion toward the second pressure application diaphragm portion when coming into contact with the outer surface of the first pressure application diaphragm portion;
first urging means for keeping the first urging diaphragm portion urged toward the second pressure application diaphragm portion;
a second urging diaphragm portion (120) arranged on the outer wall surface (50b) of the inner wall of the second chamber for pressing the second pressure application diaphragm portion toward the first pressure application diaphragm portion when coming into contact with the outer surface of the second pressure application diaphragm portion; and
second urging means for keeping the second urging diaphragm portion urged toward the first pressure application diaphragm portion.
According to a second aspect of the invention, there is provided an injector of the first aspect, wherein the first urging means includes a first piston portion (110) arranged in a first receiving space (105) outside of the first urging diaphragm to be reciprocated in contact with the first urging diaphragm portion, and a first spring (115) for keeping the first piston portion urged toward the second pressure application diaphragm portion, and wherein the second urging means includes a second piston portion (130) arranged in a second receiving space (125) outside of the second urging diaphragm portion to be reciprocated in contact with the second urging diaphragm portion, and a second spring (135) for keeping the second piston portion urged toward the first pressure application diaphragm portion.
According to a third aspect of the invention, there is provided an injector of the first aspect, wherein the supply and discharge of the working fluid for reciprocating the pressure application mechanism to and from the first chamber or the second chamber is switched for a predetermined switching period by an external switching means, which switching period can be arbitrarily changed.
According to a fourth aspect of the invention, there is provided an injector of the first aspect, wherein the center position of the pressure application mechanism is rendered to coincide with the intermediate position of the longest reciprocation range of the pressure application mechanism, or the neighborhood thereof, by the cooperation between the first urging means and the second urging means at the time of stopping the supply or discharge of the fluid.
According to a fifth aspect of the invention, there is provided an injector of the first aspect, further comprising a first inlet (11) communicating with the first outer inlet portion, a first outlet (12) communicating with the first outer outlet portion, a second inlet (33) communicating with the second outer inlet portion, and a second outlet (34) communicating with the second outer outlet portion, wherein one of the first inlet and the second inlet is closed and one of the first outlet and the second outlet is closed while the injector is in operation.
According to a sixth aspect of the invention, there is provided an injector of the first aspect, wherein the body has built therein a first intake check valve block (60) including the first outer inlet portion and the first intake check valve, a first discharge check valve block (65) including the first outer outlet portion and the first discharge check valve, a second intake check valve block (70) including the second outer inlet portion and the second intake check valve, and a second discharge check valve block (75) including the second outer outlet portion and the second discharge check valve.
According to a seventh aspect of the invention, there is provided an injector of the first aspect, wherein the working fluid for reciprocating the pressure application mechanism flows into and from only one of the first chamber and the second chamber, the injector further comprising a spring (140) interposed between the inner wall of the chamber which no working fluid flows into or from and the inner surface of the pressure application diaphragm portion arranged in the particular chamber.
According to an eighth aspect of the invention, there is provided an injector of the first aspect, further comprising a first lid portion (116) for closing from the outside the first receiving space formed outside of the first urging diaphragm portion to receive the first urging means and a second lid portion (136) for closing from outside the second receiving space formed outside of the second urging diaphragm portion to receive the second urging means, the first lid portion (116) and the second lid portion (136) being formed of a transparent or translucent material.
According to a ninth aspect of the invention, there is provided an injector of the first aspect, comprising a first inlet communicating with the first outer inlet portion, a first outlet communicating with the first outer outlet portion, a second inlet communicating with the second outer inlet portion, a second outlet caricating with the second outer outlet portion, and working fluid intrusion detection means (210) for detecting the intrusion of the working fluid into the fluid flowing out from the first outlet or the second outlet.
According to a tenth aspect of the invention, there is provided an injector of the ninth aspect, further comprising inflowing fluid properties detection means (211) for detecting the properties of the fluid flowing in from the first inlet or the second inlet.
According to an 11th aspect of the invention, there is provided an injector of the second aspect, wherein the body is formed with a first vent hole (106) for discharging outside of the body the air between the first urging diaphragm portion and the first piston portion and a second vent hole (126) for discharging outside of the body the air between the second urging diaphragm portion and the second piston portion, the injector further comprising leakage detection means (230, 231) for detecting the presence or absence of the pressured fluid leaking from the first vent hole or the second vent hole.